(i) Field of the Invention
The present invention relates to a vehicle-guiding device which is mounted on a vehicle and which leads a driver along a route to a destination, and more specifically, it relates to a device for aurally informing a driver of a road to be selected (a guide road) at a junction.
(ii) Description of the Prior Art
In order to relieve the load of a driver during driving, various devices have heretofore been investigated, and some kinds of devices are already mounted on vehicles. Among these devices, there is a vehicle-guiding device for leading a vehicle along a road to a destination by inputting the destination to the device. This vehicle-guiding device has a mechanism for informing the driver of a route to be selected at a junction such as an intersection, and some mechanisms are known by which the route is displayed on a display, or a direction to be taken is announced at an intersection by voice.
For example, Japanese Utility Model Application Laid-open No. 13413/1985 discloses a device in which a course to be taken is specified from 8 directions (front, rear, right and left directions as well as oblique right and left directions) on the basis of an angle to an incoming direction at a junction by a voice expression to lead the vehicle along the course. According to such a vehicle led by the voice, a driver need not look at a display or the like, and thus leading the vehicle along the route can be achieved without having any bad influence on the driver. In this example, when the course to be taken is almost the same as the direction of travel, the course is judged to be straight, and so the aural guidance is omitted, whereby the unnecessary guidance is inhibited.
However, the above-mentioned conventional vehicle-guiding device has the constitution for omitting the guidance only when the route to be taken is judged to be straight on the basis of an angle to the incoming direction. Therefore, if a curved route is judged to be in the range of a right or left turn, the device gives the guidance inconveniently, even when the guidance is considered to be unnecessary for the curved route.